Hector's and Māui incidents 1921 - 2008: Incident database

Introduction

View summary information of recorded Hector's and Māui incidents from 1921 to 2008.

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Incident summary to 19 March 2008 - Hector's dolphin
Cause of death		East Coast South Island	South Coast South Island	West Coast South Island	Unknown population	TOTAL
Boat strike		1				1
Euthanased					1	1
Human interaction	Harpooned	4				4
Human interaction	Other interaction	5		3		8
Possible human interaction		6		3		9
Known entanglement	Cray pot	3				3
	Recreational set net	12		9		21
	Commercial set net	41		2	2	45
	Unknown set net	15		6	1	22
	Trawl net	15		4		19
Probable entanglement	Salmon farm	1				1
	Recreational set net					0
	Commercial set net					0
	Unknown set net	1		4		5
	Unknown net	8	1	4		13
Possible entanglement	Salmon farm	1				1
	Recreational set net	1				1
	Commercial set net					0
	Unknown set net	16		10		26
	Unknown net	16	1	7		24
Trauma – unknown cause		5	1	3		9
Natural		9	2	6		17
Unknown		14	4	6		24
Not determinable		34	4	31		69
Not available		8	2	14	1	25
Not assessed		39	8	19	1	67
TOTAL		255	23	131	6	415

Of the Hector's dolphins where a cause of death was able to be assessed (254 of the 415 total animals):

35% were known to have died through entanglement in set nets; Set net entanglement may have been the cause of death for up to an additional 27% of cases where an assessment of the cause of death was made (possible or probable net entanglements)
7% were found to have died through natural causes
7% were known to have died as a result of being caught in a trawl net
A definitive cause of death could not be found for 9%
Of the total Hector's dolphin mortalities, 17% were too decomposed or were too fragmented for a cause of death to be determined. A further 16% were not assessed for cause of death (mostly historical cases).

Human interaction: No sign of net entanglement, but definite signs of other types of human interaction e.g. high degree of mutilation.
Possible human interaction: No sign of net entanglement, but indications of other types of human interaction e.g. marks that resemble knife wounds.
Trauma – unknown cause: As read from pathology report – trauma, with an unknown cause (i.e. could be natural or human-induced).
Known entanglement: Animal was known (from incident report) to have been entangled and died.
Probable entanglement: As read from pathology report, or presence of net marks on body and one other definite indication of capture e.g. mutilation.
Possible entanglement: As read from pathology report, or presence of net marks on body and a mention of this in incident report.
Natural: Cause of death deemed to be from natural causes.
Not assessed: Necropsy not completed, carcass not recovered, or no assessment of cause of death undertaken.
Not available: Necropsy or incident report not available at present.
Not determinable: Cause of death not able to be determined due to condition of carcass (decomposition, fragmentation etc).
Unknown: Cause of death unexplained or not definitive (e.g. "open" diagnosis in pathology report).